As a hydraulic control device that controls the operation of a hydraulic operating machine, JP2009-63115A discloses a device including a cylinder that extends/retracts by a working oil supplied from a pump to drive a load, a control valve that switches the supply/discharge of the working oil to/from the cylinder to control the extension/retraction operation of the cylinder, and a load-retaining mechanism that is interposed in a main passage that connects a load-side pressure chamber of the cylinder to the control valve.
The load-retaining mechanism includes an operated check valve and a meter-out control valve that operates by a pilot pressure to perform metering control and switches the operation of the operated check valve.
The switching position of the meter-out control valve is set when a spool moves by a balance between a biasing force of a spring and a thrust force of a piston operated by a pilot pressure. When the spool moves upon receiving a thrust force of the piston, the spool and piston enter a state in which their end surfaces are in contact with each other.